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Biomedical subjects

J Walls

Publications and source records attributed to J Walls.

At least 145 records · Page 8Linked to original sources
PubMed1990

Adrenal dysfunction in patients with renal amyloid.

Amyloidosis is a multi-system disease. Renal involvement often leads to end-stage renal failure, which carries a poor prognosis. This paper reports the adrenal status of 22 patients with renal amyloid who were considered for or who had been commenced on renal replacement therapy. Twelve patients were considered or found to have AA amyloid and the remaining 10 had AL amyloid. Of 16 patients tested, seven demonstrated an abnormal response to a synacthen test. Four patients died at Addisonian crisis and hypo-adrenalism probably contributed to the deaths of a further two patients. Amyloid deposition was found in the adrenal glands in seven patients who died of systemic amyloidosis and renal failure. It is recommended that all patients with renal amyloid should have an assessment of adrenal function performed and if abnormal replacement steroid therapy should be commenced.

Adrenal Gland Diseases↗
PubMed1990

Factors influencing peritoneal catheter survival in continuous ambulatory peritoneal dialysis.

The success of continuous ambulatory peritoneal dialysis (CAPD) is to a great extent determined by the survival of the peritoneal catheter. The aim of this study was to identify technical factors which influence CAPD catheter survival. A total of 453 CAPD catheters inserted into 310 patients over an 8-year period were analysed. Access to the peritoneum was gained either by an open surgical technique (n = 290) or by a closed technique using a trocar and introducer (n = 163). Data relating to a number of potentially significant risk/benefit factors were analysed using multiple regression analysis (proportional hazards method of Cox). Three factors were found to be independently associated with improved catheter survival. They were: using an open surgical insertion technique, performing a partial omentectomy at the time of catheter insertion and the procedure being performed by a consultant.

Adolescent↗
PubMed1989

Vitamin A and bone formation. Different responses to retinol and retinoic acid of chick bone cells in organ culture.

The response of bone cells in organ culture to retinol and retinoic acid was studied. Both stimulated incorporation of [3H]thymidine into DNA by 16-day embryonic chick calvaria, but the time-course of the responses differed; the peak responses to retinol and retinoic acid occurred at about 18 h and 48 h, respectively. Although retinol inhibited chick bone collagen synthesis retinoic acid had no effect, but it did stimulate non-collagenous protein synthesis, whereas the effect on the latter of retinol was, if anything, inhibitory. When present with retinol, retinoic acid was able to attenuate the inhibitory effect of the former on chick bone collagen synthesis, but preincubation with retinoic acid had no such effect. In neonatal murine calvarial cultures, retinoic acid inhibited collagen synthesis selectively in the same manner as did retinol. The ability of chick osteoblasts to respond differently to retinol and retinoic acid suggests that both forms of the vitamin may have a role in bone formation and that their intracellular models of action may differ although the attenuation response indicates there may be some interaction between the two.

Animals↗
PubMed1989

Different types of segmental sclerosing glomerular lesions in six experimental models of proteinuria.

From 133 to 615 glomeruli were examined in sections of kidneys from each of 60 animals, representing six rodent models of proteinuria. Particular attention was paid to the position of segmental lesions. Lewis rats given sheep anti-rat glomerular basement membrane antibodies had lesions almost exclusively at the glomerulo-tubular junction. Wistar rats on a diet of 24 per cent casein or with subtotal nephrectomy and a diet of 24 per cent soya had lesions mainly at the hilum. Wistar rats given bovine serum albumin had global lesions but virtually no segmental lesions. Wistar rats given puromycin aminonucleoside had lesions at the glomerulo-tubular junction and global mesangial abnormalities shortly after the treatment but later developed segmental lesions at all parts of the glomerulus. Untreated BUF/Mna rats had lesions at the glomerulo-tubular junction early in life but later had lesions at all parts of the glomerulus. Untreated NZB/NZW hybrid mice had various types of glomerulonephritis and also had lesions at the glomerulo-tubular junction. These findings showed that (1) segmental lesions at the glomerulo-tubular junction, or glomerular tip, occur in experimental animals, a fact not previously reported, and these tip changes are a common feature in several different models of proteinuria; (2) hilar segmental lesions are seen in conditions with hyperfiltration of protein; and (3) segmental lesions at various parts of the glomerulus are seen in some models of proteinuria and probably indicate late effects of random toxic damage to the glomerulus. Thus, there are at least three different types of segmental glomerular lesions in experimental animals--tip, hilar, and random--with different morphology and pathogenesis. It is likely that these findings can be extended to human renal diseases with segmental glomerular lesions. This will help to clarify the controversial and unsatisfactory term focal segmental glomerulosclerosis.

Animals↗
PubMed1989

A selection adjusted comparison of hospitalization on continuous ambulatory peritoneal dialysis and haemodialysis.

A retrospective study was made of the rate of hospitalization (days/annum) in 227 patients established on either continuous ambulatory peritoneal dialysis (CAPD) or haemodialysis (HD) between 1 January 1980 and 31 July 1985. In order to address the biases which may confound simple comparisons of morbidity when treatment allocation is non-random, multiple regression was used to identify and adjust for the effect of pre-treatment variables significantly (p less than 0.01) influencing hospitalization rate. Six significant variables were identified out of 86 studied. Adverse factors were (i) diabetes and (ii) atherosclerotic disease. Beneficial parameters were (iii) a living spouse and (iv) a controlled presentation via outpatients. The relationship (v) between age and hospitalization rate was U-shaped; the rate increasing above the age of 60 years and below the age 20. (vi) Date of commencement of dialysis exhibited a complex relationship with hospitalization rate implying that whilst the rate on HD remained relatively stable over the course of the study, that on CAPD markedly diminished. As a result, the hospitalization ratio (CAPD:HD) fell consistently throughout the study period, at an estimated annual rate of 28.3% (95% confidence limits 15.6-39.1%). For a patient starting therapy on 1 January 1980 the predicted hospitalization rate on CAPD was 7.8 times greater than that on HD (4.4-13.9) but by 1 May 1985 the estimated ratio had fallen to 1.33 (0.85-2.09). Having adjusted for important confounding, it would appear that with growing experience, hospitalization rates on CAPD fall close to those on HD.

Age Factors↗
PubMed1989

The use of calcium carbonate to treat the hyperphosphataemia of chronic renal failure.

This study evaluates the use of calcium carbonate in chronic renal failure. Forty-eight patients (25 male, 23 female, mean age 54.3 years, six pre-dialysis. 12 CAPD, 30 haemodialysis) on phosphate restriction and requiring aluminum hydroxide (mean 2.4 +/- 0.8 g/day) to control serum phosphate, were converted to an equivalent dose of calcium carbonate (2.5 +/- 0.6 g/day). None received vitamin D analogues. Three months post-conversion there was a significant decrease in mean (+/- SEM) serum phosphate (1.86 +/- 0.08 versus 1.66 +/- 0.05 mmol/l P less than 0.01) and serum aluminum (28.3 +/- 5.4 versus 13.2 +/- 3.0 micrograms/l, P less than 0.0001): calcium/phosphate product was unchanged. Post-conversion there was an increase in serum bicarbonate, (20.6 +/- 0.5 versus 22.1 +/- 0.6 mmol/l, P less than 0.01) and serum calcium (2.32 +/- 0.02 versus 2.45 +/- 0.03 mmol/l, P less than 0.0001). No change in serum creatinine, alkaline phosphatase or parathormone occurred. No adverse effects were reported but nine (18%) patients became hypercalcaemic (2.7 to 2.93 mmol/l), eight of whom responded to dose reduction. Hypercalcaemia did not correlate with pre-conversion serum calcium, parathyroid hormone, alkaline phosphatase or aluminium. Calcium carbonate is an effective alternative to aluminium-based phosphate binders. It produces a beneficial increase in serum calcium and bicarbonate and a significant decrease in serum aluminium. Hypercalcaemia is unpredictable but is easily reversible in the majority of patients.

Administration, Oral↗
PubMed1989

Body composition changes in the subtotally nephrectomized rat fed differing dietary proteins.

Changes in body composition are found in chronic uraemia, but it is unclear if this results from poor nutrient intake or is a consequence of impaired renal function. To investigate this question, 31 female Wistar rats were allocated to undergo subtotal nephrectomy or sham operation and were fed diets of either 24% casein or 24% soya protein. Three months later measurements of inulin clearance were undertaken in the conscious animal and the carcass subsequently analyzed for body water and body fat. Subtotally nephrectomized animals had a significantly greater proportion of body water (p less than 0.001) and a lesser proportion of body fat (p less than 0.001) than control animals, and a significant correlation was found between glomerular filtration rate and body fat content (24% casein diet: r = 0.96; 24% soya diet: r = 0.71). The dietary protein source appeared not to influence the body composition. These results support the concept that altered body composition in uraemia is due to renal dysfunction rather than altered nutrient intake.

Adipose Tissue↗
PubMed1989

Does increasing haemoglobin concentration and haematocrit have a pressor effect in dialysis patients?

The haemodynamic consequences of differing rates of rise of haemoglobin and haematocrit in haemodialysis and CAPD patients were examined. Pre-dialysis mean arterial pressure, weight and haematological indices were recorded in 100 established haemodialysis patients prior to a 2-unit blood transfusion and repeated, pre-dialysis, within 1 week. Haemoglobin rose from 6.7 +/- 0.2 to 9.3 +/- 0.1 g/dl, weight was unchanged, and there was a small fall in mean arterial pressure. Similar indices were recorded, including the mid-arm circumference (MAC) in 100 CAPD patients 1 month after starting CAPD and at the time of maximum haemoglobin within the first year. Haemoglobin rose from 8.5 +/- 0.1 to 10.7 +/- 0.1 g/dl, weight increased slightly, but there was no change in MAC: weight ratio and there was a small fall in mean arterial pressure. In neither group was there a change in antihypertensive medication. In conclusion, increasing the haemoglobin concentration and haematocrit of dialysis patients within the range described in this study did not promote elevated blood pressure.

Adult↗
PubMed1989

Seizures in haemodialysis patients treated with recombinant human erythropoietin.

Administration of recombinant erythropoietin (r-HuEPO) is an effective treatment for the anaemia of chronic renal failure, but in some patients it has been accompanied by elevated blood pressure. This study focuses on seven patients with end-stage renal failure, managed on haemodialysis, who developed probable hypertensive encephalopathy with seizures during treatment with r-HuEPO. All made a full recovery. The events were not clearly related to the haemoglobin concentrations achieved, and four patients have subsequently been restarted on r-HuEPO therapy at a reduced dose, resulting in a slower increase in haemoglobin with no recurrence of episodes of severe hypertension. Close attention needs to be paid to blood pressure in patients commencing erythropoietin therapy, and it seems prudent to aim for a gradual increase in haemoglobin concentration to allow the circulation to adapt to changes in oxygen delivery and haematocrit.

Adult↗
PubMed1989

The metabolic consequences of the correction of acidosis in uraemia.

Chronic renal failure is associated with increased protein turnover, and recent evidence suggests that this may be due to the accompanying acidosis. Patients with stable chronic renal failure maintained on protein restriction were given sodium bicarbonate supplementation for 8 weeks. This resulted in improvements in acid-base status, plasma urea and uric acid levels, independent of changes in glomerular filtration rate. Acidosis is a potentially reversible toxic effect of chronic renal failure and its correction produces sustained metabolic benefit.

Acidosis, Renal Tubular↗
PubMed1989

Formulation change in VLCD in response to DHSS recommendations: comparative evaluation.

Response to recommendations of the Committee on Medical Aspects of Food Policy prompted reformulation of the 330 kcal Cambridge diet to 405 kcal per day with 42 g protein. Developmental trials demonstrated that clinical performance of VLCD formulations at comparable calorie levels could not be assumed. Studies using the formulation commercially produced as Cambridge diet extra with female subjects showed no significant difference in weight losses between the original and the new diet products over 2 or 8 week study periods. The percentage of body weight represented by FFM rose in the 8-week trial by 5 per cent in each group. Blood analyses were carried out before and after 8 weeks dieting with the 405 kcal formula. All parameters remained in the normal range, except iron, which was slightly below normal prior to the trial and rose into the normal range by week 8. These findings compared favourably with previous blood profiles of subjects using the 330 kcal formula. Modifications of the formula which increased the protein and calorie content to 42 g and 405 kcal respectively did not significantly alter the efficacy and safety of the product.

Body Composition↗